Synthesis, Structure, and Chemoselective Reactivity of N‐(2‐Iodylphenyl)acylamides: Hypervalent Iodine Reagents Bearing a Pseudo‐Six‐Membered Ring Scaffold

Abstract

A pseudo‐benziodoxazine structure with intramolecular secondary I⋅⋅⋅O bonding, as shown by X‐ray analysis, is seen in a series of N‐(2‐iodylphenyl)acylamides prepared from 2‐iodoaniline (see scheme). These compounds contain a six‐membered pseudocyclic scaffold about an iodine(V) center and are able to oxidize either alcohols or sulfides, with the reactivity depending largely on the substitution pattern on the amide group adjacent to the iodyl moiety.

N-(2-Iodylphenyl)acylamides - New Pentavalent Iodine Oxidizing Reagents

“…8 An observed I···O distance of 2.647 Å is typical for iodine(V) pseudo-cyclic moieties; 4 the resulting pseudo-benziodoxazine scaffold is not planar. Overall, the formation of a six-membered pseudocycle in NIPA leads to several unique features in the solidstate structure.…”

“…8 Diversity on the amide nitrogen atom of the prepared NIPAs was introduced by changing from hydrogen (series 15), a small substituent capable of forming H-bonds, to methyl group (series 16), also relatively small, but unable to form Hbonds, and finally to a relatively bulky benzyl group (series 17). Also, a cyclic derivative 18 was prepared.…”

“…8 All products were isolated as stable, white solids. No detonation or violent decomposition was observed during either heating of the NIPA compounds in a sealed or an open capillary tube, or upon impact.…”

Hypervalent iodine(V) reagents in organic synthesis

“…On the other hand, 1,6-arrangement of iodine and oxygen atoms results in a non-planar six-membered ring of pseudo-benziodoxazines 91. Generally, the distance between the iodine and oxygen atoms amounts to 2.6 -2.7 Å in pseudo-benziodoxoles 90 and pseudo-benziodoxazines 91, [128][129][130][131][132][133][134] …”

“…[128][129][130][131][132][133][134] In recent years, pseudo-benziodoxoles and pseudobenziodoxazines have found increasing practical application in organic synthesis as efficient oxidizing reagents.…”